1. Field of the Invention
This invention relates generally to systems for telephonic communications and, more particularly, to a method and apparatus for determining an optimum sequence of telephone numbers to forward calls that have been made to a personal telephone number. The invention further relates to systems based on artificial intelligence techniques, particularly those using knowledge processing, and especially to adaptive or trainable systems that create sets of rules and use parallel distributed processing components.
2. Description of the Related Art
Telecommunication service companies have begun to experiment with systems that employ "personal telephone numbers." Personal telephone numbers are assigned to individuals rather than to specific physical telephone instruments. When a call is made to an individual's personal telephone number, the call is forwarded to a telephone instrument at one of a number of locations depending upon the whereabouts of the individual at a particular time. The primary difficulty in effectively implementing personal telephone numbers involves accurately determining to which physical telephone instrument to forward calls.
Several approaches have been suggested for addressing this problem. These approaches can be categorized into the "find me" and "follow me" methodologies. Systems employing the "find me" approach typically forward calls to a personal telephone number to telephone instruments according to a preset sequence and until the subscriber is located. The "follow me" systems forward calls to a personal telephone number to telephone instruments according to recent activity of the subscriber.
For example, Jordan et al. (U.S. Pat. No. 4,313,035) proposes a system for keeping track of the location of the individual and routing calls to the telephone where the individual can be found at a particular time, or indicating to the caller that the individual is in transit between locations. One significant problem with this system is that it requires the individual to make a call to update a system database whenever he changes location.
Bissell et al. suggests another solution in U.S. Pat. No. 5,243,645. This patent discloses a system that forwards calls made to a personal telephone number (or to an ordinary number) based on information obtained when an individual subscriber engages in an activity, such as credit card calls, credit card transactions, or automated teller transactions, that indicates his location. When such an activity is performed, the location of the individual, potentially including the telephone number, is recorded in a database that tracks the location of the subscriber. Calls can then be forwarded to the specific telephone number associated with the last known location of the subscriber, or to the telephone number in the subscriber's defined list of calls that is nearest to the last known location as indicated by the area code, cellular region, paging area, etc.
One problem with this solution is that it provides a forwarding location for calls to a personal telephone number that may be available for only a limited time. The new number is valid only as long as the subscriber stays at the location where he performed that activity.
There are also many difficulties in building such a system, including problems of integrating and coordinating databases and communications systems built for different purposes. For example, systems managing credit card transactions must notify the call-forwarding system of a subscriber's whereabouts when the subscriber engages in a transaction using his credit card. This requires the credit card system to store information of call-forwarding subscribers and notify the call-forwarding service when the credit card transaction takes place.
Another way to resolve the call-forwarding dilemma is proposed by Brennan et al. in U.S. Pat. No. 5,329,578. This patent discloses a system that routes calls to a personal telephone number to physical locations of telephone instruments according to information in a "service profile" set up by the subscriber. The subscriber defines a sequence of numbers to locate the subscriber. Call routing thus depends on a schedule specified by the subscriber, i.e., the day and time of a call. In addition, the system described in this patent can route calls according to the calling line identification (e.g., refusing to take calls from certain numbers) and according to the urgency of the call (e.g., playing a prerecorded announcement indicating that only emergency calls are being taken, and asking if the call is an emergency and routing accordingly).
One drawback to the "service profile" approach is the difficulty in entering the data, especially from a telephone, which requires a complex interactive voice response interface. While a customer service representative can help create the service profile, perhaps using a desktop workstation and graphical user interface, use of a representative for this task is inefficient. Also, this approach is inflexible, requiring changes to the service profile should the subscriber change his or her pattern of activity either permanently or temporarily. Moreover, many subscribers are not sufficiently aware of their own pattern of activity to create an accurate schedule.
While the approach of having the system try a sequence of calls, i.e., the "find me" approach, is often effective, it is typically inefficient because it requires the caller to wait while the system rings three or four times at each number in the sequence. It is thus very desirable to have a method for using the "find me" approach that is both easy to set up and maintain and that can determine a sequence of numbers to call at a given time that minimizes the number of calls necessary to reach the subscriber.